A motor drive device including an inverter and the like converts a direct-current voltage into an alternating-current voltage by using a switching operation of a switching element. Therefore, noise (switching noise) is generated by the switching operation of the switching element. This noise propagates to outside via a power supply line to cause influences on devices.
Conventionally, to reduce the influences on a power supply line and the like, a noise filter is inserted and connected between an alternating-current power supply and a motor drive device. In the noise filter, an input-side capacitor, a common-mode choke coil, and an output-side capacitor are connected in this order between the alternating-current power supply and the motor drive device.
Patent Literature 1 describes that, at the time of manufacturing a noise filter inserted between an alternating-current power supply and an electronic device, an input-side capacitor, a common-mode choke coil, and an output-side capacitor are placed on a wiring board having a printed wiring pattern made of conductive foil configured on an insulating layer, cream solder is sandwiched between electrode parts of the respective components and the printed wiring pattern, and a high-temperature heating element is caused to contact an underside of the wiring board. According to Patent Literature 1, it is supposed that the solder is melted and all the components can be soldered at a time.